This section provides background information related to the present disclosure which is not necessarily prior art.
Shearing tools, such as hedge trimmers, are commonly employed in the maintenance of landscape to trim vegetation. Such shearing tools commonly have a pair of shearing blades that can be moved relative to one another to shear a workpiece, such as a branch of a shrub. Shearing motion of the blades is commonly responsive to the operator's use of a trigger switch that is integrated into the shearing tool.
It is relatively commonplace for the shearing blades to jam on occasion, as when attempting to cut a workpiece that is relatively large in cross-sectional area or when cutting several workpieces simultaneously. In such situations, the operator of a prior art shearing tool has very limited capability to un-jam the shearing blades. For example, the operator could release and re-activate the trigger switch, but doing so would merely stop and restart the motor that provides power to the shearing blades; because the jammed workpiece is disposed between the shearing blades and the shearing blades have no additional momentum, it is unlikely that merely stopping and re-starting the motor will be effective in un-jamming the shearing blades of the shearing tool. A remaining option is to pull the workpiece out of the shearing blades, for example by tugging on the shearing tool.
A shearing tool that is disclosed in U.S. Patent Application Publication No. 2009/0188361 is configured with a control means that changes the direction of the movement of the shearing blade(s) automatically in response to an event sensed by the control means. The event could be an increase in or a high value of a cutting load or the activation of a trigger switch that is operated by the user of the shearing tool to cause the motor to operate. One problem that we have noted with this configuration concerns the inability of the control means to distinguish between a workpiece and a foreign object, such as fencing or netting. We have noted that often times it would not be desirable to attempt to cut through a foreign object that has (inadvertently) become jammed between the shearing blades. Accordingly, there remains a need in the art for an improved shearing tool having capabilities for unjamming a set of jammed shearing blades.